This invention relates to a high speed winding device for textured yarns and, more particularly, to a vertically mounted high speed winding device for parallel plied textured yarns.
As used herein the term "high winding speed" means a yarn speed in the range of from at least 400 meters per minute to about 1000 meters per minute. The term "parallel plied textured yarn" means two false twist textured yarn strands, one having "S" twist and the other "Z" twist, for example as produced by a double ended draw texturing process and laid in parallel onto a package. The term "helix angle" means the acute angle between the helix or convolution of the yarn and a diametrical plane intersecting the convolution.
Several winding devices known in the art utilize a relatively low speed, full traverse stroke initially, the stroke length being gradually reduced as the yarn package builds in order to produce a package with conical ends. When such a winding device is used for high speed winding of parallel plied textured yarn, the yarn is laid down on the package at a low helix angle because of the high yarn speed to traverse speed ratio. Moreover, parallel plied textured yarn wound on a package on such a winding device exhibits an apparent lack of bundle cohesion. As a consequence of the low helix angle and lack of bundle cohesion, the parallel plied textured yarn on removal from the package over the end thereof tends to snag, to split into its two components and to spiral around the package as it is dragged over the package surface. The above yarn take-off characteristics and the high take-off tension resulting therefrom make packages of parallel plied textured yarn wound on such a winding device unsuitable for being fed directly to a knitting machine. In the past a separate ply-twisting step has often been added to overcome this take-off problem with parallel plied textured yarn.
High speed winding devices which utilize a full stroke traverse, wind yarn at a high helix angle and produce stable, low tension cylindrical or bi-conical packages have recently become available. However, these winding devices are complex and expensive and may require "fanning guide distance" to "stroke length" ratios as high as 5:1; the "fanning guide distance" being the distance from the traverse guide to the last guide the yarn touches prior to the traverse guide. Such high "fanning guide distance" to "stroke length" ratios, which greatly increase the building space required to house the winding devices, are required because of the very high traverse speeds required to achieve the reasonably uniform tension and the high helix angle required for acceptable package formation at high winding speeds.
U.S. Pat. No. 3,730,448 which issued May 1, 1973 to H. Schippers et al. discusses a horizontally mounted relatively low speed, winding device which utilizes a full traverse stroke initially, the stroke length being gradually reduced as the package builds in order to produce a package with conical ends. A modification allowing rapid changes in package taper angles and means of superimposing intermittent stroke reduction in order to avoid so-called hard edges at the yarn reversal points are also discussed in U.S. Pat. No. 3,730,448.
French Pat. No. 1,579,444, publication date Aug. 22, 1969, discloses a horizontally mounted winding device for wire in which stroke modulation is achieved by mounting a V-grooved pulley on a full stroke traversing guide to guide the wire onto a spool. The pulley is mounted in a skew position on its axis, i.e., not perpendicular thereto, and the axis of the pulley is parallel to the axis of the spool. Thus, as the pulley rotates a sinusoidal pattern of low amplitude and relatively high frequency is superimposed on the laydown pattern of the low speed full stroke traversing guide.
A V-grooved pulley guide similar to that disclosed in French Pat. No. 1,579,444 may be combined with a winding device of the type discussed in aforementioned U.S. Pat. No. 3,730,448 to produce a horizontally mounted winding device that is useful for winding many types of yarns at very high winding speeds. However, this combination does not provide a vertically mounted winding device for winding yarn at high speeds. Neither does it provide a winding device which will "exercise the yarn" being wound on package as appears to be required to achieve good bundle cohesion in parallel plied textured yarn being wound at high winding speeds. As used herein, the term "exercise the yarn" means to impart a vibratory motion to parallel plied textured yarn immediately before it is wound on a package, such that the "S" twist and the "Z" twist yarn strands are intermingled to give bundle cohesion to the yarn. As the distance travelled by the yarn would remain constant as the V-grooved pulley rotates, no vibratory motion would be imparted to the yarn by the pulley. As used herein the term "vibratory motion" means repetitive changes in the distance travelled by the yarn which occur at a high frequency and result in a high frequency variation in the tension of the yarn.
It is an object of this invention to provide a vertically mounted high speed winding device for winding parallel plied textured yarn on a biconical package, in which the yarn is laid down with a substantial angle between successive yarn wraps on the package and in which a vibratory motion is imparted to the yarn immediately before it is laid down on the package.